光纤光栅在金属锈蚀传感中的应用

Application of Fiber Bragg Gratings in Monitoring Metal Corrosion

介绍了一种基于光纤布拉格光栅(FBG)应变敏感特性的金属锈蚀传感器。该器件由光纤光栅、有预应力的钢弹簧和一些机械部件组合而成。组合后的弹簧处于压缩状态。在弹簧弹力的作用下,光纤光栅的峰值波长增长了3.2 nm。对该器件进行了加速腐蚀实验:将其放入盐酸环境中,逐日监测光纤光栅峰值波长的变化,发现峰值波长逐渐缩短,说明弹簧的弹性系数随着弹簧的锈蚀而逐渐减小。到弹簧锈蚀断裂,整个锈蚀过程持续了1315 h,平均锈蚀速率约5μm/d。实验表明了该传感器在实际应用中的可能性。同时讨论了光纤光栅的温度效应及其他影响其实用性的因素。

Sensors for monitoring metal materials corrosion are of much significance for civil engineering structures. By using the strain-sensitive characteristics of fiber Bragg gratings （FBG）, a metal corrosion sensor is proposed and demonstrated in this paper. The device was made of a fiber grating, a steel spring and some mechanical parts, and was packaged under pre-strained condition of the spring. The peak wavelength of the grating was re＆shifted by 3.2 nm in stretch strain and the spring was pressed after packaging. The device was then put in an atmosphere with hydrochloric acid. The peak wavelength was monitored every day, and was found to be blue-shifted little by little~ showing the elastic coefficient of the spring was decreased gradually that was caused by the corrosion of the spring material. The accelerated corrosion process lasted 1315 hours until the spring was broken, and an average etching rate was estimated to be 5 μm/day. The experiment showed that the device may be used as a sensor for metal corrosion if it is put in the same ambient as the engineering structure. Temperature effect of the FBG, friction in the device and other factors related to its practical use are discussed in the paper.